Vacuum assisted wound dressing

Abstract

Apparatus for the application of topical negative pressure therapy to a wound site is described, the apparatus comprising: a wound contacting element for retaining wound exudate fluid therein; a wound covering element that provides a substantially airtight seal over the wound contacting element and wound site; a vacuum connection tube connecting a wound cavity to a vacuum source; and a vacuum source connected to a distal end of the vacuum connection tube.

What is claimed is: 
     
       1. An apparatus for the application of topical negative pressure therapy to a wound site, the apparatus comprising:
 a wound contacting element comprising an absorbent member for retaining wound exudate fluid therein; 
 a wound covering element that provides a substantially airtight seal over the wound contacting element and wound site, wherein the wound covering element comprises an aperture; 
 a vacuum connection tube connectable to the wound covering element; 
 a valve interposed between the wound contacting element and the vacuum connection tube when the vacuum connection tube is connected to the wound covering element, wherein the valve is sealed to the wound covering element at the aperture in the wound covering element, wherein the valve is configured to block all liquid transport beyond itself away from the wound site and allow air transport beyond itself away from the wound site; 
 wherein the wound contacting element and the wound covering element are combined in a single physical entity; 
 wherein the valve comprises a flange that bears against an underside of the wound covering element and a circular shoulder and recess which is held in the aperture of the wound covering element; 
 a cup-shaped member seated onto a surface of the wound covering element over the valve; and 
 wherein the wound covering element is a flexible element configured to be roughly level with surrounding skin. 
 
     
     
       2. An apparatus according to  claim 1  wherein the valve blocks all liquid transport beyond itself away from the wound site and allows air transport beyond itself away from the wound site under pressures between atmospheric pressure and 200 mmHg below atmospheric pressure. 
     
     
       3. An apparatus according to  claim 2  where the valve blocks all liquid transport beyond itself away from the wound site and allows air transport beyond itself away from the wound site between atmospheric and 250 mmHg below atmospheric pressure. 
     
     
       4. An apparatus according to  claim 1  wherein the valve comprises a liquid contact triggered valve. 
     
     
       5. An apparatus according to  claim 1  wherein liquid transport is blocked by the wound contacting element being able to absorb but not transmit liquid under the applied negative pressure. 
     
     
       6. An apparatus according to  claim 5  wherein the wound contacting element is a self-coalescent material. 
     
     
       7. An apparatus according to  claim 6  where the self-coalescent material is selected from the group comprising: carboxymethylchitosan; and a derivative of carboxymethylchitosan. 
     
     
       8. An apparatus according to  claim 4  wherein the liquid contact-triggered valve is constructed of an absorbent material placed in a restricted aperture. 
     
     
       9. An apparatus according to  claim 8  wherein the absorbent material is able to absorb but not transmit fluid under the applied negative pressure. 
     
     
       10. An apparatus according to  claim 1  wherein coupling of the vacuum connection tube to the wound covering element is by non-adhesive means. 
     
     
       11. An apparatus according to  claim 10  wherein coupling is achieved by a surface-to-surface pressure differential. 
     
     
       12. An apparatus according to  claim 1  wherein the wound contacting element, the wound covering element and the vacuum connection tube are combined into a single physical entity. 
     
     
       13. An apparatus according to  claim 1  wherein the vacuum connection tube may be repeatedly connected and disconnected from the wound covering element without damage thereto. 
     
     
       14. An apparatus according to  claim 1 , further comprising a vacuum source configured to provide vacuum to the vacuum connection tube. 
     
     
       15. An apparatus for the application of topical negative pressure therapy to a wound site, the apparatus comprising:
 a wound covering element configured to be positioned over a wound, wherein the wound covering element comprises an aperture; 
 a cup-shaped member separate from the wound covering element and seated onto a surface of the wound covering element and configured to be secured over the aperture in the wound covering element, the cup-shaped member comprising a radially outwardly-extending flange portion defining a lower opening configured to seat onto an upper surface of the wound covering element surrounding the aperture and form a seal with the wound covering element; 
 a vacuum connection tube configured to be connected to the cup-shaped member; and, 
 a wound dressing portion configured to substantially prevent all wound exudate from being aspirated into the vacuum connection tube or out of the wound dressing portion, the wound dressing portion comprising an absorbent material configured to be placed over the wound and under the wound covering element, the absorbent material configured to retain wound exudate therein upon application of negative pressure; 
 wherein the cup-shaped member includes a liquid blocking material held underneath the cup-shaped member and mounted at the lower opening defined by the flange portion, wherein the liquid blocking material is configured to substantially prevent all wound exudate from being aspirated into the vacuum connection tube; and 
 wherein the wound covering element is a flexible element configured to be roughly level with surrounding. 
 
     
     
       16. The apparatus of  claim 15 , wherein the wound dressing portion comprises a valve that closes upon contact with wound exudate and blocks all liquid transport beyond itself away from the wound site. 
     
     
       17. The apparatus of  claim 15 , wherein the wound dressing portion is a wound contacting element. 
     
     
       18. The apparatus of  claim 15 , wherein the wound dressing portion and the wound covering element form a single element. 
     
     
       19. The apparatus of  claim 15 , wherein the absorbent material comprises a superabsorbent material. 
     
     
       20. The apparatus of  claim 19 , wherein the superabsorbent material is capable of absorbing at least five times its own weight in fluid. 
     
     
       21. The apparatus of  claim 15 , wherein the absorbent material comprises a non-woven material. 
     
     
       22. The apparatus of  claim 15 , wherein the absorbent material comprises an open-celled foam. 
     
     
       23. The apparatus of  claim 15 , wherein the absorbent material comprises a knit or woven material. 
     
     
       24. The apparatus of  claim 15 , wherein the wound covering element additionally comprises an adhesive for adhering to a portion of skin surrounding the wound. 
     
     
       25. The apparatus of  claim 15 , wherein the wound covering element is fluid impermeable and gas permeable. 
     
     
       26. The apparatus of  claim 15 , wherein the wound covering element is gas permeable. 
     
     
       27. The apparatus of  claim 15 , further comprising a vacuum source configured to provide vacuum to the vacuum connection tube. 
     
     
       28. The apparatus of  claim 27 , wherein the vacuum source comprises a battery and the vacuum source and battery together weigh less than 200 g. 
     
     
       29. A method for the application of topical negative pressure therapy to a wound site, the method comprising:
 placing a wound dressing portion comprising an absorbent material over the wound site;
 sealing the wound site with a flexible wound covering capable of providing a substantially airtight seal over the wound site, the flexible wound covering being roughly level with surrounding skin; 
 
 applying topical negative pressure to the wound site through a conduit connected to the wound covering via a cup-shaped member separate from the wound covering and seated onto a surface of the wound covering element and secured over an aperture in the wound covering element, the cup-shaped member comprising a radially outwardly-extending flange portion that defines a lower opening, wherein a liquid blocking element is mounted at the lower opening in the flange portion and held relative to the cup-shaped member; 
 retaining fluid from the wound site in the absorbent material; and, 
 preventing substantially all liquid from the wound site from entering the conduit with the liquid blocking element, wherein the liquid blocking element blocks substantially all liquid transport beyond itself away from the wound site. 
 
     
     
       30. The method of  claim 29 , wherein the absorbent material is a superabsorber. 
     
     
       31. The method of  claim 30 , wherein the superabsorber absorbs at least five times its own weight in fluid. 
     
     
       32. The method of  claim 29 , wherein preventing fluid from entering the cup-shaped member comprises operating a valve that occludes upon contact with fluid from the wound site. 
     
     
       33. The method of  claim 29 , wherein the wound dressing portion and the wound covering element are placed over the wound site as a single element. 
     
     
       34. The method of  claim 29 , wherein the wound dressing portion is placed into contact with the wound. 
     
     
       35. The method of  claim 29 , wherein topical negative pressure is applied with a powered vacuum source. 
     
     
       36. The method of  claim 29 , wherein substantially no liquid is aspirated out of the absorbent material. 
     
     
       37. The method of  claim 29 , wherein the wound dressing portion and the wound covering are combined in a single physical entity, and wherein the absorbent material and the wound covering are placed simultaneously over the wound site.